Integrated circuits are manufactured by a highly complex manufacturing process. The manufacturing conditions may vary from one manufacturing process iteration to another iteration.
Accordingly, identical integrated circuits that ideally share the same design and are expected to be equal, actually differ from each other due to the semiconductor manufacturing process variations. Thus, a first integrated circuit can be faster and of a higher leakage than a second integrated circuit which design is ideally identical to the first integrated circuit.
Each manufacturing process is characterized by an allowed manufacturing process window that may include multiple process cases such as best process case, worst process case typical process case and the like.
Best process case integrated circuits are the fastest integrated circuits but exhibit the highest leakage current. Worst process case integrated circuits are the slowest integrated circuits and exhibit the lowest leakage current. Typical process case provides integrated circuits that are slower than best process case integrated circuits and are faster than worst process case integrated circuits.
Integrated circuits can be required to operate at a certain speed and to consume up to an allowable level of current. These contradicting demands can reduce the yield of the manufacturing process—as some integrated circuits can be too slow but comply to the current consumption requirements whilst some integrated circuits will exhibit a too high current consumption but comply with the speed requirements.